Pin control method and substrate processing apparatus

ABSTRACT

A substrate processing apparatus includes a processing container; a placement table; a plurality of pins provided on the placement table configured to perform delivery of the substrate; a plurality of drivers configured to vertically drive the plurality of pins, respectively; a plurality of measuring devices each including an encoder configured to measure height positions of the plurality of pins, respectively. The substrate processing apparatus also includes a controller configured to: measure the height positions of the plurality of pins; select a reference pin; estimate a reference height position; calculate an adjustment speed for making the height positions of the pins other than the reference pin match with the estimated reference height position; and control the drivers, which drive the other pins, to adjust driving speeds of the other pins to an adjustment speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 15/951,583, filed on Apr. 12, 2018, which claims priority toJapanese Patent Application No. 2017-080697, filed on Apr. 14, 2017, thedisclosures of which are incorporated herein in their entirety byreference, and priority is claimed to each of the foregoing.

TECHNICAL FIELD

Various aspects and exemplary embodiments of the present disclosurerelate to a pin control method and a substrate processing apparatus.

BACKGROUND

In a substrate processing apparatus that perform a substrate processingsuch as, for example, etching or film formation, a plurality of pins isprovided on a placement table so as to protrude and retreat from aplacement surface of the placement table on which a substrate such as,for example, a semiconductor wafer is placed. Then, as the pins areraised or lowered, the delivery of the substrate is carried out. As amethod of controlling the plurality of pins, for example, there is amethod of vertically driving a base member, to which the plurality ofpins is attached, by a single driving unit so as to raise or lower theplurality of pins collectively via the base member. See, e.g., JapanesePatent Laid-Open Publication No. 2011-054933.

SUMMARY

According to an aspect of the present disclosure, there is provided apin control method including measuring respective height positions of aplurality of pins, which is vertically driven respectively by aplurality of driving units while supporting a substrate, selecting areference pin, which serves as a reference for speed control, from theplurality of pins using the measured height positions of the pluralityof pins, estimating, with respect to the selected reference pin, areference height position, which is a height position after apredetermined time has passed since the height positions of theplurality of pins were measured, and calculating an adjustment speed formaking the height positions of the pins other than the reference pinmatch with the estimated reference height position, and controlling thedriving units, which drive the other pins, to adjust driving speeds ofthe other pins to the adjustment speed.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating a substrate processingapparatus according to one exemplary embodiment.

FIG. 2 is an enlarged cross-sectional view of a stage ST of thesubstrate processing apparatus illustrated in FIG. 1.

FIG. 3 is a flowchart illustrating an exemplary flow of a pin controlmethod according to one exemplary embodiment.

FIG. 4 is a view illustrating a specific example of a pin control methodaccording to one exemplary embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawing, which form a part hereof. The illustrativeembodiments described in the detailed description, drawing, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

The technique described above has a problem in that a difference occursbetween the height positions of the plurality of pins depending on theinclination of the base member, and as a result, the position of thesubstrate supported by the plurality of pins deviates from apredetermined position.

On the other hand, a method that does not use a base member isconsidered as follows. For example, a method is considered in which aplurality of driving units is independently provided for a plurality ofpins and the plurality of pins is respectively driven by the pluralityof driving units. However, in this method, a difference occurs betweenthe height positions of the plurality of pins due to unevenness in thedriving speeds of the respective pins, and as a result, there is apossibility that of the positional deviation of the substrate occurs.

A pin control method according to one aspect disclosed here includes:measuring respective height positions of a plurality of pins, which isvertically driven respectively by a plurality of driving units whilesupporting a substrate; selecting a reference pin, which serves as areference for speed control, from the plurality of pins using themeasured height positions of the plurality of pins; estimating, withrespect to the selected reference pin, a reference height position,which is a height position after a predetermined time has passed sincethe height positions of the plurality of pins were measured; calculatingan adjustment speed for making the height positions of the pins otherthan the reference pin match with the estimated reference heightposition; and controlling the driving units, which drive the other pins,to adjust driving speeds of the other pins to the adjustment speed.

In the above-described pin control method, the selecting includesselecting, as the reference pin, the pin with a lowest height positionor a highest height position, from the plurality of pins when themeasured height positions of the plurality of pins do not match witheach other.

In the above-described pin control method, the estimating includes:calculating a driving speed of the reference pin at a measurementtiming, at which the height positions of the plurality of pins aremeasured, based on a passed time from start of driving of the pluralityof pins by the plurality of driving units to the measurement timing andthe height position of the reference pin measured at the measurementtiming; and estimating the reference height position based on thecalculated driving speed of the reference pin, the predetermined time,and the height position of the reference pin measured at the measurementtiming.

In the above-described pin control method, the measuring includes newlymeasuring the respective height positions of the plurality of pinswhenever the predetermined time has passed since the height positions ofthe plurality of pins were measured last time, and the selectingprocessing, the estimating processing, and the adjusting processing arerepeatedly executed until the newly measured height positions of theplurality of pins match with each other.

In the above-described pin control method, the adjusting includescontrolling the driving units, which drive the other pins, to adjust thedriving speeds of the other pins to a driving speed of the reference pinwhen the height positions of the plurality of pins match with eachother.

In the above-described pin control method, the height positions of theplurality of pins are positions of tip ends of the plurality of pins onthe basis of a placement surface of a placement table for the substrateor a reference surface that is lower than the placement surface by apredetermined distance.

A substrate processing apparatus according to one aspect disclosed hereincludes: a processing container; a placement table provided in theprocessing container and configured to place a substrate thereon; aplurality of pins provided on the placement table so as to protrude andretreat from the placement surface of the placement table and configuredto perform delivery of the substrate; a plurality of driving unitsconfigured to vertically drive the plurality of pins, respectively; aplurality of measuring devices configured to measure height positions ofthe plurality of pins, respectively; and a controller configured to:measure the respective height positions of the plurality of pins, whichis vertically driven respectively by the plurality of driving unitswhile supporting the substrate; select a reference pin, which serves asa reference for speed control, from the plurality of pins using themeasured height positions of the plurality of pins; estimate, withrespect to the selected reference pin, a reference height position,which is a height position after a predetermined time has passed sincethe height positions of the plurality of pins were measured; calculatean adjustment speed for making the height positions of the pins otherthan the reference pin match with the estimated reference heightposition; and control the driving units, which drive the other pins, toadjust driving speeds of the other pins to the adjustment speed.

According to one aspect of a pin control method disclosed here, it ispossible to prevent misalignment of a substrate.

Hereinafter, exemplary embodiments of a pin control method and asubstrate processing apparatus disclosed herein will be described indetail with reference to the drawings. Further, in the respectivedrawings, similar components will be denoted by similar referencenumerals.

FIG. 1 is a view schematically illustrating a substrate processingapparatus according to one exemplary embodiment. FIG. 1 illustrates across section of the substrate processing apparatus according to theexemplary embodiment.

As illustrated in FIG. 1, the substrate processing apparatus 10 of theexemplary embodiment is a parallel flat plate type plasma processingapparatus. The substrate processing apparatus 10 includes a processingcontainer 12. The processing container 12 has a substantiallycylindrical shape, and defines a processing space S as an inner spacetherein. The substrate processing apparatus 10 includes a stage ST inthe processing container 12. The stage ST is a placement table on whicha semiconductor wafer (hereinafter referred to as “wafer”) W as a targetprocessing substrate is placed. In one exemplary embodiment, the stageST includes a stand 14 and an electrostatic chuck 50. The stand 14 has asubstantially disk shape and is provided below the processing space S.The stand 14 is formed of aluminum, for example, and constitutes a lowerelectrode.

In one exemplary embodiment, the substrate processing apparatus 10further includes a cylindrical holding unit 16 and a cylindrical supportunit 17. The cylindrical holding unit 16 is in contact with edgeportions of the side surface and the bottom surface of the stand 14, andholds the stand 14. The cylindrical support unit 17 extends in thevertical direction from the bottom portion of the processing container12, and supports the stand 14 via the cylindrical holding unit 16.

The substrate processing apparatus 10 further includes a focus ring 18.The focus ring 18 is placed on the upper surface of a peripheral edgeportion of the stand 14. The focus ring 18 is a member for improvingin-plane uniformity of the processing accuracy of the wafer W. The focusring 18 is a plate-shaped member having a substantially annular shape,and is formed of, for example, silicon, quartz, or silicon carbide.

In one exemplary embodiment, an exhaust path 20 is formed between thesidewall of the processing container 12 and the cylindrical support unit17. A baffle plate 22 is attached to an inlet of the exhaust path 20 orin the middle thereof. Further, an exhaust port 24 is provided in thebottom portion of the exhaust path 20. The exhaust port 24 is defined byan exhaust pipe 28, which is fitted in the bottom portion of theprocessing container 12. An exhaust device 26 is connected to theexhaust pipe 28. The exhaust device 26 has a vacuum pump, and maydecompress the processing space S in the processing container 12 to apredetermined degree of vacuum. A gate valve 30 is attached to thesidewall of the processing container 12 to open and close thecarry-in/out port of the wafer W.

A high-frequency power supply 32 for plasma generation is electricallyconnected to the stand 14 via a matcher 34. The high-frequency powersupply 32 applies high-frequency power having a predetermined highfrequency (e.g., 13 MHz) to a lower electrode, that is, the stand 14.

The substrate processing apparatus 10 further includes a shower head 38in the processing container 12. The shower head 38 is provided above theprocessing space S. The shower head 38 includes an electrode plate 40and an electrode support body 42.

The electrode plate 40 is a conductive plate having a substantially diskshape and constitutes an upper electrode. A high-frequency power supply35 for plasma generation is electrically connected to the electrodeplate 40 via a matcher 36. The high-frequency power supply 35 applieshigh-frequency power having a predetermined high frequency (e.g., 60MHz) to the electrode plate 40. When high-frequency power is applied tothe stand 14 and the electrode plate 40 by the high-frequency powersupply 32 and the high-frequency power supply 35, respectively, ahigh-frequency electric field is formed in the space between the stand14 and the electrode plate 40, that is, in the processing space S.

A plurality of gas vent holes 40 h is formed in the electrode plate 40.The electrode plate 40 is detachably supported by the electrode supportbody 42. A buffer chamber 42 a is provided inside the electrode supportbody 42. The substrate processing apparatus 10 further includes a gassupply unit 44, and the gas supply unit 44 is connected to a gasintroduction port 25 of the buffer chamber 42 a via a gas supply conduit46. The gas supply unit 44 supplies a processing gas to the processingspace S. The processing gas may be, for example, a processing gas foretching or a processing gas for film formation. In the electrode supportbody 42, a plurality of holes, each continuing to a corresponding one ofthe plurality of gas vent holes 40 h, is formed, and the plurality ofholes communicate with the buffer chamber 42 a. The gas supplied fromthe gas supply unit 44 is supplied to the processing space S through thebuffer chamber 42 a and the gas vent holes 40 h.

In one exemplary embodiment, a magnetic field forming mechanism 48 isprovided on the ceiling portion of the processing container 12 so as toextend annularly or concentrically. The magnetic field forming mechanism48 functions to facilitate the start of high-frequency discharge (plasmaignition) in the processing space S and stably maintain the discharge.

In the substrate processing apparatus 10, the electrostatic chuck 50 isprovided on the upper surface of the stand 14. The electrostatic chuck50 includes a pair of insulating films 54 a and 54 b and an electrode 52sandwiched between the pair of insulating films 54 a and 54 b. A DCpower supply 56 is connected to the electrode 52 via a switch SW. When aDC voltage is applied from the DC power supply 56 to the electrode 52, aCoulomb force is generated, and the wafer W is attracted to and held onthe electrostatic chuck 50 by the Coulomb force.

In one exemplary embodiment, the substrate processing apparatus 10further includes a gas supply line 58 and a heat transfer gas supplyunit 62. The heat transfer gas supply unit 62 is connected to the gassupply line 58. The gas supply line 58 extends to the upper surface ofthe electrostatic chuck 50 and extends annularly on the upper surface.The heat transfer gas supply unit 62 supplies a heat transfer gas suchas, for example, He gas to the space between the upper surface of theelectrostatic chuck 50 and the wafer W.

(Configuration of Stage ST)

FIG. 2 is an enlarged cross-sectional view of the stage ST of thesubstrate processing apparatus illustrated in FIG. 1. As illustrated inFIG. 2, the stage ST has a placement surface PF. The placement surfacePF includes a first region R1 and a second region R2. The first regionR1 is a region for placing the wafer W. In one exemplary embodiment, thefirst region R1 is defined by the upper surface of the electrostaticchuck 50, and is a substantially circular region. The first region R1 isan example of the placement surface of the stage ST. The second regionR2 is a region for placing the focus ring 18, and is provided annularlyso as to surround the first region R1. In one exemplary embodiment, thesecond region R2 is defined by the upper surface of a peripheral edgeportion of the stand 14.

A plurality of pins 70 is provided on the stage ST so as to protrude andretreat from the placement surface of the stage ST (that is, the firstregion R1). The plurality of pins 70 is provided, for example, in aplurality of holes equidistantly provided in the circumferentialdirection of the stage ST via seal members such as, for example,O-rings. In one exemplary embodiment, three holes are equidistantlyprovided in the circumferential direction, and three pins 70 areprovided in the three holes.

The plurality of pins 70 is independently connected to a plurality ofdriving units 72 (see FIG. 1), and is vertically driven by the pluralityof driving units 72, respectively. For example, each driving unit 72includes a motor and a ball screw, and converts the rotational motion ofthe motor into linear motion by the ball screw, thereby raising orlowering each pin 70. Then, as the plurality of pins 70 is raised, thedelivery of the wafer W is performed between the plurality of pins 70and a transfer arm, which transfers the wafer W into the processingcontainer 12 via the gate valve 30. Then, as the plurality of pins 70 towhich the wafer W has been delivered is lowered, the wafer W is placedon the placement surface of the stage ST (that is, the upper surface ofthe second region R1).

Further, a plurality of measuring devices (not illustrated) such as, forexample, encoders is provided in the plurality of driving units 72, andthe plurality of measuring devices measure the height positions of theplurality of pins 70 respectively. Here, the height positions of theplurality of pins 70 are the positions of the tip ends of the pluralityof pins 70 on the basis of the placement surface of the stage ST or areference surface that is lower than the placement surface by apredetermined distance.

Returning to the description of FIG. 1, in one exemplary embodiment, thesubstrate processing apparatus 10 further includes a controller 66. Thecontroller 66 is connected to the exhaust device 26, the switch SW, thehigh-frequency power supply 32, the matcher 34, the high-frequency powersupply 35, the matcher 36, the gas supply unit 44, and the heat transfergas supply unit 62. The controller 66 sends a control signal to each ofthe exhaust device 26, the switch SW, the high-frequency power supply32, the matcher 34, the high-frequency power supply 35, the matcher 36,the gas supply unit 44, and the heat transfer gas supply unit 62. By thecontrol signal from the controller 66, exhaust by the exhaust device 26,the opening and closing of the switch SW, the supply of power from thehigh-frequency power supply 32, the impedance adjustment of the matcher34, the supply of power from the high-frequency power supply 35, theimpedance adjustment of the matcher 36, the supply of the processing gasby the gas supply unit 44, and the supply of the heat transfer gas bythe heat transfer gas supply unit 62 are controlled.

In the substrate processing apparatus 10, the processing gas is suppliedfrom the gas supply unit 44 to the processing space S. Further, ahigh-frequency electric field is formed between the electrode plate 40and the stand 14, that is, in the processing space S. Thereby, plasma isgenerated in the processing space S, and a processing of the wafer W isperformed by, for examples, radicals of elements contained in theprocessing gas. Further, the processing of the wafer W may be anarbitrary processing, and may be, for example, etching of the wafer W orfilm formation on the wafer W, but is not limited thereto.

Further, the controller 66 controls the plurality of driving units 72 soas to perform a pin control method to be described later. To give adetailed example, the controller 66 measures the respective heightpositions of the plurality of pins 70, which is vertically driven by theplurality of driving units 72 while supporting the wafer W. Then, thecontroller 66 selects a reference pin, which serves as the reference forspeed control, from the plurality of pins 70 using the measured heightpositions of the plurality of pins 70. Then, the controller 66 estimatesa reference height position, which is the height position after apredetermined time has passed since the height positions of theplurality of pins 70 were measured, with respect to the selectedreference pin. Then, the controller 66 calculates the adjustment speedfor making the height positions of the pins other than the reference pinmatch with the estimated reference height position, and controls thedriving units 72, which drive the other pins, to adjust the drivingspeeds of the other pins to the adjustment speed. Here, the heightpositions of the plurality of pins 70 are the positions of the tip endsof the plurality of pins 70 on the basis of the placement surface of thestage ST or the reference surface that is lower than the placementsurface by a predetermined distance. Further, the height positions ofthe plurality of pins 70 are measured respectively using a plurality ofmeasuring devices (not illustrated) such as, for example, encodersprovided in the plurality of driving sections 72, respectively.

Next, a pin control method according to one exemplary embodiment will bedescribed. FIG. 3 is a flowchart illustrating an exemplary flow of a pincontrol method according to one exemplary embodiment. Further, here, theflow of a processing in a case where, as the plurality of pins 70 israised, the delivery of the wafer W is performed between the pluralityof pins 70 and the transfer arm, which transfers the wafer W into theprocessing container 12 through the gate valve 30, will be described.

As illustrated in FIG. 3, when the wafer W is transferred into theprocessing container 12 by the transfer arm, the controller 66 of thesubstrate processing apparatus 10 starts driving the plurality of pins70 (step S101). At this time, the driving speeds of the plurality ofpins 70 are set to the same speed.

The controller 66 stands by until a predetermined timing (hereinafterreferred to as “measurement timing”) for measuring the height positionsof the plurality of pins 70 arrives (No in step S102). Then, when themeasurement timing arrives (Yes in step S102), the controller 66measures the respective height positions of the plurality of pins 70(step S103).

The controller 66 determines whether or not the height positions of allof the pins 70 reach a predetermined position using the measured heightpositions of the plurality of pins 70 (step S104). The predeterminedposition is, for example, the position determined so that the wafer W,transferred from the transfer arm to the plurality of pins 70, does notinterfere with the transfer arm. When the height positions of all of thepins 70 reach the predetermined position (Yes in step S104), thecontroller 66 ends the processing.

On the other hand, when the height positions of all of the pins 70 havenot reached the predetermined position (No in step S104), the controller66 determines whether or not the measured height positions of theplurality of pins 70 match with each other (step S105). Here, since thedriving speeds of the plurality of pins 70 are set to the same speed atthe start of driving of the plurality of pins 70, in principle, theheight positions of the plurality of pins 70 will match with each other.However, since the plurality of pins 70 is provided, for example, in theplurality of holes, which is provided in the stage ST, via the sealmembers such as, for example, O-rings, the state of friction between therespective pins 70 and the seal members may be uneven. When the state offriction between the respective pins 70 and the seals member is uneven,the driving speeds of the plurality of pins 70 may be uneven, and as aresult, there may be the difference between the height positions of theplurality of pins 70.

When the measured height positions of the plurality of pins 70 do notmatch with each other (step S105 No), the controller 66 selects areference pin, which serves as the reference for speed control, from theplurality of pins 70 based on the height positions of the plurality ofpins 70 (step S106). For example, the controller 66 selects, as thereference pin, the pin 70 having the lowest height position or thehighest height position, from the plurality of pins 70.

Subsequently, the controller 66 estimates, with respect to the selectedreference pin, a reference height position, which is the height positionof the reference pin after a “predetermined time” has passed since theheight positions of the plurality of pins 70 were measured (step S107).Specifically, the controller 66 calculates the driving speed of thereference pin at the measurement timing based on the passed time fromthe start of driving of the plurality of pins 70 to the measurementtiming and the height position of the reference pin measured at themeasurement timing. Then, the controller 66 estimates the referenceheight position based on the calculated driving speed of the referencepin, the aforementioned “predetermined time”, and the height position ofthe reference pin measured at the measurement timing.

Subsequently, the controller 66 calculates an adjustment speed formaking the height positions of the pins other than the reference pinmatch with the estimated reference height position (step S108).Specifically, the controller 66 calculates the adjustment speed based onthe reference height position, the height positions of the other pins atthe measurement timing, and the aforementioned “predetermined time”.

Subsequently, the controller 66 controls the driving units 72, whichdrive the other pins, to adjust the driving speeds of the other pins tothe adjustment speed (step S109). In this way, since the driving speedsof the other pins are adjusted to the adjustment speed for making theheight positions of the other pins match with the reference heightposition, the difference between the height position of the referencepin and the height positions of the pins, other than the reference pin,is prevented at a point in the time when the “predetermined time” haspassed. As a result, it is possible to prevent misalignment of the waferW due to the difference between the height positions of the pins 70,which supports the wafer W.

Subsequently, the controller 66 stands by until the aforementioned“predetermined time” passes (No in step S110). Then, when the“predetermined time” has passed (Yes in step S110), the controller 66returns the processing to step S103 in order to newly measure therespective height positions of the plurality of pins 70. Thereby, theheight positions of the plurality of pins 70 are newly measured wheneverthe aforementioned “predetermined time” has passed since the heights ofthe plurality of pins 70 were measured last time. Then, the selection ofthe reference pin, the estimation of the reference height position, andthe adjustment of the driving speeds of the other pins are repeatedlyexecuted until the newly measured height positions of the plurality ofpins 70 match with each other (step S103, No in step S104, No in stepS105, and steps S106 to S110). Thereby, since the height positions ofthe plurality of pins 70 may continuously match with each other,misalignment of the wafer W may be further prevented.

On the other hand, when the measured height positions of the pluralityof pins 70 match with each other (Yes in step S105), the controller 66determines whether or not the driving speeds of the respective pins 70match with each other (step S111). When the driving speeds of therespective pins 70 match with each other (Yes in step S111), thecontroller 66 returns the processing to step S103 since it is notnecessary to adjust the driving speed.

On the other hand, when the driving speeds of the respective pins 70 donot match with each other (No in step S111), the controller 66 performsthe following processings since the driving speeds of the other pins aretemporarily adjusted to the adjustment speed. That is, the controller 66controls the driving units 72, which drive the other pins 70, to adjustthe driving speeds of the other pins to the driving speed of thereference pin (step S112), and returns the processing to step S103.Since the driving speeds of the other pins are adjusted to the drivingspeed of the reference pin, the driving speeds of the respective pins 70match with each other.

Next, a specific example of the pin control method illustrated in FIG. 3will be described with reference to FIG. 4. FIG. 4 is a viewillustrating a specific example of a pin control method according to oneexemplary embodiment. In FIG. 4, the horizontal axis represents the timeand the vertical axis represents the height positions of the pluralityof pins 70. Here, it is assumed that three pins 70 (pins #1 to #3) areprovided as the plurality of pins 70.

First, driving of the pins #1 to #3 is started at a certain time 0. Atthis time, the driving speeds of the pins #1 to #3 are set to the samespeed.

After the driving of the pins #1 to #3 is started, the respective heightpositions of the pins #1 to #3 are measured at a time t1, which is themeasurement timing. In the example of FIG. 4, a height position h₂ ofthe pin #2 and a height position h₃ of the pin #3 match with each other,and a height position h₁ of the pin #1 is lower than the height positionh₂ of the pin #2 and the height position h₃ of the pin #3. That is, dueto the friction between the pin #1 and the corresponding seal member,the driving speed of pin #1 is slower than the initially set speed atthe time t₁.

Then, a reference pin, which serves as the reference for speed control,is selected from the pins #1 to #3 using the measured height positionsh₁ to h₃. In the example of FIG. 4, the pin #1 having the lowest heightposition, from the pins #1 to #3, is selected as the reference pin.

When the pin #1 is selected as the reference pin, with respect to thepin #1, a reference height position h₁′, which is the height position ata time t₂ when a predetermined time α has passed from the time t₁, isestimated. Specifically, the driving speed v₁ of the pin #1 at the timet₁ is calculated based on the passed time t₁ from the time 0 to the timet₁ and the height position h₁ of the reference pin (that is, the pin #1)measured at the time t₁. The driving speed v₁ of the pin #1 isrepresented by the following Equation (1).v ₁ =h ₁ /t ₁  (1)

Then, the reference height position h₁′ is estimated based on thecalculated driving speed v₁ of the pin #1, the predetermined time α, andthe height position h₁ of the pin #1 measured at the time t₁. Thereference height position h₁′ is represented by the following Equation(2).h ₁ ′=h ₁ +α·v ₁  (2)

When the reference height position h₁′ is estimated, the adjustmentspeed v₂ for making the height positions of the pins other than thereference pin (that is, the pin #1) match with the reference heightposition h₁′ is calculated. Since the height position h₂ of the pin #2matches with the height position h₃ of the pin #3, here, it is assumedthat the pins, other than the reference pin, are the pin #2.Specifically, the adjustment speed v₂ for making the height position ofthe pin #2 match with the reference height position h₁′ is calculatedbased on the reference height position h₁′, the height position h₂ ofthe other pin (that is, the pin #2) at the time t₁, and thepredetermined time α. The adjustment speed v₂ is represented by thefollowing Equation (3).v ₂=(h ₁ ′−h ₂)/α  (3)

Further, since the height position h₂ of the pin #2 matches with theheight position h₃ of the pin #3, the adjustment speed v₃ for making theheight position of the pin #3 match with the reference height positionh₁′ is represented by Equation (4) as follows.v ₃=(h ₁ ′−h ₃)/α=(h ₁ ′−h ₂)/α=v ₂  (4)

Subsequently, the driving units 72, which drive the other pins (that is,the pins #2 and #3), are controlled so that the driving speeds of thepins #2 and #3 are adjusted to the adjustment speed v₂. Thereby, at thetime t₂ when the predetermined time α has passed from the time t₁, thedifference between the height position of the pin #1, which is thereference pin, and the height positions of the pins #2 and #3, which arethe pins other than the reference pin, is prevented. In the example ofFIG. 4, the difference between the height positions of the pins #1 to #3is zero at the time t₂.

As described above, according to one exemplary embodiment, therespective height positions of the plurality of pins 70, which isvertically driven respectively by the plurality of driving units 72,while supporting the wafer W, are measured, and the reference pin, whichserves as the reference for speed control, is selected from theplurality of pins 70 using the measured height positions of theplurality of pins 70. Then, with respect to the selected reference pin,the reference height position, which is the height position after thepredetermined time has passed since the height positions of theplurality of pins 70 were measured, is estimated. Then, the adjustmentspeed for making the height positions of the pins other than thereference pin match with the estimated reference height position iscalculated, and the driving units 72, which drive the other pins, arecontrolled so that the driving speeds of the other pins are adjusted tothe adjustment speed. Therefore, the difference between the heightpositions of the plurality of pins 70 is prevented. As a result, it ispossible to prevent misalignment of the wafer W due to the differencebetween the height positions of the plurality of pins 70, which supportsthe wafer W.

OTHER EMBODIMENTS

In the above exemplary embodiment, the pin control method in a case ofraising the plurality of pins 70 has been described by way of example,but the disclosed pin control method may be applied to a case oflowering the plurality of pins 70. In other words, the disclosed pincontrol method may be applied in a case of lowering the plurality ofpins 70, to which the wafer W has been transferred from the transferarm, toward the stage ST. In this case, in the flowchart illustrated inFIG. 3, in a case of determining whether or not the height positions ofall of the pins 70 reach the predetermined position (step S104), forexample, the placement surface or the reference surface that is lowerthan the placement surface by a predetermined distance may be adopted asthe “predetermined position”.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A substrate processing apparatus comprising: aprocessing container; a placement table provided in the processingcontainer and configured to place a substrate thereon; a plurality ofpins provided on the placement table so as to protrude and retreat fromthe placement surface of the placement table and configured to performdelivery of the substrate; a plurality of driving units configured tovertically drive the plurality of pins, respectively; a plurality ofmeasuring devices each including an encoder configured to measure heightpositions of the plurality of pins, respectively; and a controllerconfigured to: measure the height positions of the plurality of pins,which is vertically driven respectively by the plurality of drivingunits while supporting the substrate; select a reference pin, whichserves as a reference for speed control, from the plurality of pinsusing measured height positions of the plurality of pins; estimate, withrespect to the selected reference pin, a reference height position,which is a height position after a predetermined time has passed sincethe height positions of the plurality of pins were measured; calculatean adjustment speed for making the height positions of the pins otherthan the reference pin match with the estimated reference heightposition; and control the driving units, which drive the other pins, toadjust driving speeds of the other pins to the adjustment speed.
 2. Thesubstrate processing apparatus according to claim 1, wherein, when thereference pin is selected, the controller is further configured toselect, as the reference pin, a pin having a lowest height position or ahighest height position, from the plurality of pins when the measuredheight positions of the plurality of pins do not match with each other.3. The substrate processing apparatus according to claim 1, wherein,when the reference height position is estimated, the controller isfurther configured to calculate a driving speed of the reference pin ata measurement timing where the height positions of the plurality of pinsare measured, based on a passed time from start of driving of theplurality of pins by the plurality of driving units to the measurementtiming and the height position of the reference pin measured at themeasurement timing; and estimate the reference height position based onthe calculated driving speed of the reference pin, the predeterminedtime, and the height position of the reference pin measured at themeasurement timing.
 4. The substrate processing apparatus according toclaim 1, wherein, when the respective height positions are measured, thecontroller is further configured to newly measure the respective heightpositions of the plurality of pins whenever the predetermined time haspassed since the height positions of the plurality of pins were measuredlast time, and repeatedly, select, estimate, and adjust until the newlymeasured height positions of the plurality of pins match with eachother.
 5. The substrate processing apparatus according to claim 4,wherein, when the driving speeds are adjusted, the controller is furtherconfigured to control the driving units, which drive the other pins, toadjust the driving speeds of the other pins to a driving speed of thereference pin when the height positions of the plurality of pins matchwith each other.
 6. The substrate processing apparatus according toclaim 1, wherein the height positions of the plurality of pins arepositions of tip ends of the plurality of pins on the basis of aplacement surface of a placement table for the substrate or a referencesurface that is lower than the placement surface by a predetermineddistance.